Databases, such as relational databases, typically include tables that are analyzed for responding to queries. For example, for a relational database, a collection of tables of data items are typically formally described and organized using a relational model. The tables may include column constraints, such as unique keys, primary keys, or foreign keys. For example, a unique key may include one or more data attributes of a data entity in a table. A primary key may uniquely specify a tuple within a table, in that, a primary key uniquely defines the characteristics of each row of the table. A foreign key is a field in a relational table that matches the primary key column of another table.